Superphthalocyanine uranium complexes

Invariably hydrolytic instability of lanthanide Por complexes, particularly that observed for the larger lanthanide elements, negatively influences their prospective application in terms of biomedicine (Sect. 7.4). As a response to this problem, larger porphyrin-like or expanded porphyrins , the so-called texaphyrins (Tx), have been examined by Sessler et al. [246]. The motivation, that expanded systems better accommodate larger ions, was previously demonstrated in a uranyl superphthalocyanine (SPc) complex [247], This SPc-complex contains an expanded, cyclic five-subunit pentakis(2-iminoisoindoline) which is formed by a template reaction of o-dicyanobenzene with anhydrous uranyl chloride. The uranium is displaced by only 0.02 A from the mean N5-plane. 

Complexes with 2,3,9,10,16,17,23,24,30,31-decaalkyl superphthalocyanines, (4,5-R2)5PcU02 (R = Me, Bu"), and the analogous pentamethylphthalocyanine complex, (4-Me)5PcU02, have been reported. In these the uranium atom is bonded to five nitrogen atoms of the superphthalocyaninate group.369... 

The apparent contradiction between the empirical stoichiometry and the spectral characteristics of these new uranyl complexes was finally resolved by X-ray crystallography. Specifically, a single crystal X-ray structural analysis of the blue-black material formed from the reaction of the anhydrous uranyl chloride and o-dicyanobenzene [112] (Figures 22 and 23) revealed that the complex obtained was in fact an expanded five-subunit superphthalocyanine macrocycle in which a pentagonal bipyramidal coordination geometry pertains about the centrally-bound uranium atom. 

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